Developments in next-generation sequencing allowed for huge strides in characterising genetic variation. However, most of our understanding of genotype-phenotype associations comes from studies conducted in controlled laboratory conditions. Although growth chambers and greenhouses provide regulated conditions, they also exclude intricate environmental cues that plants respond to in nature. Due to genotype-by-environment interactions (GxE), individuals with different genetic backgrounds may respond differently to the environment. Therefore, controlled laboratory environments offer limited understanding of how genetic differences between individuals relate to fitness differences in nature. Arabidopsis thaliana is ideal for studying the ecological genetics of flowering plants due the species’ wide range of genomic resources. The questions we aim to answer are: What is the genetic basis of early life history traits in A. thaliana? What environmental factors are contributing to observed phenotypic differences? How does GxE influence the phenotypic variation of these early life history traits? We grew 500 A. thaliana accessions from the 1001 Genomes Project in a common garden experiment on a roof in Toronto, which better mimics the species’ natural environment compared to controlled laboratory conditions. Young A. thaliana seedlings were transplanted onto the rooftop early in winter and we collected early life mortality data a month later.
Results/Conclusions:
Our results indicate that germination time is significantly correlated to latitude of origin, where accessions from higher latitudes germinated earlier compared to those from lower latitudes. To determine how GxE may be influencing phenotypic variation, we compared the germination time of individuals grown in our experiment to individuals of the same accession grown in a growth chamber, thus allowing us to compare the phenotype of individuals from the same genetic background that were exposed to different environmental conditions. Our findings suggest that GxE does contribute to the observed phenotypic variation which implies that the genetic architecture of germination time may differ depending on growth conditions. Our results also suggest that there is no correlation between latitude and early life mortality, which is surprising given that accessions from higher latitudes are expected to have been exposed to harsher winter conditions compared to accessions from lower latitudes. These results provide ecological and evolutionary context to phenotypic variation in A. thaliana by highlighting how genetic variation and environment influence phenotypic diversity of ecologically important early life history traits.
